Forgetfulness and confusion can be signs of a previously incurable condition: Alzheimer’s disease. It is the most common form of dementia, currently affecting around 50 million people worldwide. Older people in particular get sick. The fact that this number will increase sharply in the future is also related to the general increase in life expectancy.
If a suspicion of dementia is to be clarified, the affected person has to undergo neuropsychological examinations, laboratory tests and complex procedures in the hospital. However, the first neurodegenerative changes in the brain can be detected decades before reduced mental performance becomes apparent. Currently, these can only be detected by expensive or invasive procedures. These methods are therefore not suitable for extensive early screening on a larger scale. Empa researchers are working together with partners from the Cantonal Hospital and the St. Gallen Geriatric Clinic on a non-invasive diagnostic method for the early detection of symptoms of dementia.
signs in the unconscious
For the new method, the research team led by Patrick Eggenberger and Simon Annaheim from Empa’s “Biomimetic Membranes and Textiles” laboratory in St. Gallen built on a sensor belt that has already been used successfully for ECG measurements and is now equipped with sensors for other relevant parameters such as body temperature and gait pattern. Because before the ability to remember diminishes in dementia, the finest changes appear in the brain, which are expressed via the autonomic nervous system, which controls unconscious bodily processes.
Measurements over a longer period of time are required to precisely record changes in these parameters. “It should be possible to integrate the long-term measurements into everyday life,” emphasizes Simon Annaheim. For measurements that are suitable for everyday use, skin-friendly and comfortable measuring systems are essential. The diagnostic belt is therefore based on flexible sensors with electrically conductive or light-conducting fibers as well as sensors for measuring movement and temperature.
So that such long-term measurements can be used to monitor cognitive health, the researchers integrate the data recorded into specially developed mathematical models. The goal: an early warning system that can estimate the course of cognitive impairments. Another advantage: the data measurements can be integrated into telemonitoring solutions and can thus improve patient care in a familiar environment.
Suspicious monotony
In principle, the human body is able to keep its temperature constant in the range of 1 degree Celsius. Characteristic fluctuations in these values occur over the course of the day. This daily rhythm changes with age and is noticeable in neurodegenerative diseases such as dementia or Parkinson’s. In Alzheimer’s patients, for example, the core body temperature is increased by up to 0.2 degrees Celsius. At the same time, the amplitudes of the daily temperature fluctuations are muted.
In a recent study, the researchers have now been able to show that changed skin temperature values measured with the sensor belt actually provide an indication of the cognitive performance of test subjects – before dementia develops. The test subjects in the studies were healthy people with or without mild brain disorders. This mild cognitive impairment (MCI) does not constitute a handicap in everyday life, but it is considered a possible precursor to Alzheimer’s. The subjects took part in long-term measurements and neuropsychological tests. It turned out that a lower body temperature, which fluctuates more throughout the day, was linked to better brain performance. In people with MCI, body temperature varied less and was slightly elevated overall.
Train mental fitness
The heartbeat is also subject to natural fluctuations that show how our nervous system adapts to current challenges. The little stillness between two heartbeats, about a second short, has great significance for our health: if the pause stays the same, the nervous system is not in top form.
A study by researchers from ETH Zurich found that poorer readings in older, healthy people could be improved within six months through cognitive-motor dance training. In these “exergames”, the test subjects danced step sequences from a video. Participants who instead only trained straight ahead on a treadmill, but also trained their memory, benefited less.
“The point is to intervene early with suitable training as soon as the first negative signs can be measured,” says Patrick Eggenberger. “With our sensor system, any improvements in cognitive performance through movement-based forms of therapy can be tracked.” Studies with long-term measurements should now clarify how the course of mild brain disorders can be predicted on the basis of sensor measurements.